Many industrial, commercial and household applications require the breaking up of relative large objects into smaller pieces. The reduction process is variously referred to as cutting, chipping, shredding, mulching, or grinding depending in part on the size of the end product. Chipping is historically accomplished by a rotatably driven disc which produces particulate matter or chips ranging from about ¾ inches and above. Some chippers have been designed which are portable and are capable of processing at least small branches into wood chips which can then be gathered at the site of the tree trimming operation or can be distributed on the ground whereupon the chips will naturally decay without causing environmental pollution.
The rotatably driven disc is the heart of any chipper apparatus and typically includes a relatively thick metal disc mounted for rotation about a fixed axis and has at least one cutter knife mounted adjacent to a slot in the disc. The disc is rotatably driven at relatively high speeds and is typically mounted in a chamber of a housing. As material is fed toward the disc, the knife continually cuts and slices the material to form chips which pass through the chip slot in the disc to a rear side of the disc. The chips are forced from the rear side of the disc in part by centrifugal force. A discharge chute extends from the disc housing and carries the chips for discharge from the chipper apparatus.
Some materials, such as grass, leaves, needles and small branches which are inevitably fed with the other materials into the chipper apparatus but which are not cut by the knife on the rotating disc can pass to the rear side of the rotary disc. As the disc rotates, some of these materials tend to move toward the center of the rotary disc and can become entangled with the shaft about which the disc rotates. Of course, a buildup of these entangled materials about the rotating disc shaft can cause both significant and costly damages to the chipper apparatus. During operation, the chipping operation must be occasionally halted to untangle such materials from about the shaft. This downtime adds to the overall cost of the chipping operation.
Thus, there is a continuing need and desire for a chipping apparatus which is designed to inhibit the continuing buildup and entanglement of materials about the shaft on which the rotary chipping disc is mounted.